Several students of political rhetoric suggest Senator Obama's moving speech in Philadelphia Tuesday could stand with some of the great speeches in American history.

True, say some, the Democratic presidential candidate was forced into giving a speech that would explain his relationship to the Rev. Jeremiah Wright Jr., the outspoken minister of Obama's church, known for some antiwhite and anti-American sermons.

While argument continues over whether Obama's explanation was sufficient, his speech did seem to achieve this: It has sparked a conversation about race relations, one of the frankest Americans have had since the civil rights era.

"It was as thoughtful as King's 'Letter from Birmingham Jail,' with the added dimension that it was in a political context, in which [Obama] showed courage rather than merely doing the safe denunciation," says Walter Isaacson, president of the Aspen Institute and biographer of several American historical figures. "He wrestled with the most important issue we have faced throughout our history, and he did it in a way that wasn't politically calculating, but was intensely personal as well as insightful."

Not everyone agrees that the speech avoided political calculation – or that it is destined for the history books.

While well-crafted, it was "high-level hooey," concludes Peter Robinson, a Hoover Institution fellow and Reagan speechwriter, who wrote the famous "Tear down this wall!" speech. Ultimately, he says, Obama tried to diminish the importance of his close relationship with Mr. Wright by backing up to look at several centuries of race relations in America. "But when you ponder what he was actually saying ... you see that he didn't address [his relationship with Wright]. He didn't make it go away," says Robinson.

He also wonders if the speech will hurt Obama in the end, since he's built his campaign on the idea that he transcends race and politics. "This shows that he's not different; he's not transcendent. He's an extremely intelligent, well-spoken politician, but he's a politician," says Robinson. "What he needs to defeat Hillary Clinton in Pennsylvania and to defeat McCain in the general election are what we used to call Reagan Democrats, and I don't think they're going to go for this."

The speech generated conversations Wednesday at the water-cooler and lots of chatter in cyberspace as Americans e-mailed the text to one another and offered their own interpretations.

Some considered whether it was fair to put Wright's inflammatory statements about America on the same level as the comments of Obama's white grandmother, who Obama noted had "on more than one occasion uttered racial or ethnic stereotypes that made me cringe."

Others welcomed such a personal and direct look at race, and hoped it would advance the national conversation no matter what happens to Obama's candidacy.

"I appreciate that he's taking the platform he's on to say things no politician has said before," says Keith Gilmore, a black man who works at the University of Chicago's business school. "Now politicians know to speak to people directly and honestly. We're looking at race in a different way now."

In Manhattan, Doug Mohrmann, an older white man, was less certain. "I think he adequately divorced himself from some of the more controversial statements," he says. "But I think 20 years of being with that pastor and 20 years of being with that church, and totally committing to that guy and to not have addressed that kind of rhetoric before…. It's just unacceptable."

Some fervent admirers of both the speech and Obama acknowledge that it was risky. It's unusual for a political candidate still in a primary race to be so candid on such a delicate subject, and it's still unclear what the political fallout will be.

Both blacks and whites are likely to be offended by some of his statements, says Theodore Sorensen, President Kennedy's close adviser and speechwriter, and an Obama advocate. The speech also reminded listeners of the racial element in Obama's candidacy, legitimizing discussion of the issue – all of which undercuts the notion that his best chance for winning is to make voters forget about race.

But Mr. Sorensen admired the speech for that risk-taking. "This was a historic speech," he says. "I don't know of any presidential campaign speech by anyone, including even John F. Kennedy, that had as much courage and principle and long-term importance on the most fundamental problem that has faced this country since its founding, and that's the problem of race."

Historians and speechwriters compared the address to Kennedy's famous Houston speech, in which he tackled all the doubts about his Catholicism head-on. As with Kennedy's religion, Obama's race is an aspect of his candidacy that he needed to address publicly at some point, they say. And in many ways, race is a more difficult subject to broach.

"We didn't fight a war over Catholicism," says Stephen Hess, a Brookings Institution fellow and a speechwriter for Dwight Eisenhower. "It was too bad [Obama] had to do this on the basis of his relationship with a rabble rouser, which was awkward, but he used it to make much grander points about race."

On the rhetoric itself, writers lauded the speech's direct, conversational language as well as its nuance and complexity. "It was a sophisticated and honest analysis of the problem," says Terry Edmonds, former director of speechwriting for President Clinton, who called it "one of the best speeches on race in the last 20 years."

Whether American voters agree is still an open question. Even those who believe the address is destined for the annals of great American oratory are unsure.

"As a speech, it was bold, clear, well organized, eloquent in its description of history and current issues and future dreams and ideals that people of good will all share," says Sorensen. "Whether the political strategy was brilliant we'll find out later."